title: YjbH-enhanced proteolysis of Spx by ClpXP in Bacillus subtilis is inhibited by the small protein YirB (YuzO).
abstract: The Spx protein of Bacillus subtilis is a global regulator of the oxidative stress response. Spx concentration is controlled at the level of proteolysis by the ATP-dependent protease ClpXP and a substrate-binding protein, YjbH, which interacts with Spx. A yeast two-hybrid screen was carried out using yjbH as bait to uncover additional substrates or regulators of YjbH activity. Of the several genes identified in the screen, one encoded a small protein, YirB (YuzO), which elevated Spx concentration and activity in vivo when overproduced from an isopropyl-β-D-thiogalactopyranoside (IPTG)-inducible yirB construct. Pulldown experiments using extracts of B. subtilis cells producing a His-tagged YirB showed that native YjbH interacts with YirB in B. subtilis. Pulldown experiments using affinity-tagged Spx showed that YirB inhibited YjbH interaction with Spx. In vitro, YjbH-mediated proteolysis of Spx by ClpXP was inhibited by YirB. The activity of YirB is similar to that of the antiadaptor proteins that were previously shown to reduce proteolysis of a specific ClpXP substrate by interacting with a substrate-binding protein.
authors.affiliation: Department of Science & Engineering, Division of Environmental & Biomolecular Systems, Oregon Health & Science University, 20000 NW Walker Rd., Beaverton, OR 97006, USA.
authors.forename: Sushma
authors.initials: S
authors.lastname: Kommineni
authors.forename: Saurabh K
authors.initials: SK
authors.lastname: Garg
authors.forename: Chio Mui
authors.initials: CM
authors.lastname: Chan
authors.forename: Peter
authors.initials: P
authors.lastname: Zuber
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D005816:Genetic Complementation Test; D013997:Time Factors; D020798:Two-Hybrid System Techniques; D015854:Up-Regulation
chemical_list: D001426:Bacterial Proteins